Graph query language (GQL)
GQL is used to calculate values that are used in the graphs, tables and figures that can be viewed in the model. GQL is used in gqueries, see the section about Writing gqueries for more information.
Graph Query Language (GQL) is case sensitive. Since all GQL functions are written in caps, this means that all functions must be written in caps in order to function.
Functions
Math functions
The math functions consists of functions that perform mathematical operations or calculations on numerical data. Some example functions are COUNT(), SUM(), DIVIDE() can be found here as well as comparing functions like GREATER() or EQUALS().
COUNT(values)
Returns how many values. Removes nil values, but does not remove duplicates.
COUNT(V(foo,bar))
=> 2
Multiple LOOKUPS (does not remove duplicates)
COUNT(V(foo,bar), V(foo))
=> 3
Duplicates in one LOOKUP (does remove duplicates)
COUNT(V(foo,bar,foo))
=> 2
NEG(values)
Returns the first number as a negative.
NEG(2)
=> -2
NEG(1,2,3)
=> -1
AVG(values)
Returns the average of all number (ignores nil values).
AVG(1,2)
=> 1.5
AVG(1,2,3)
=> 2
AVG(1,nil,nil,2)
=> 1.5
SUM
Returns the sum of all numbers (ignores nil values).
SUM(1,2)
=> 3
SUM(1,nil)
=> 1
PRODUCT(values)
Multiplies all numbers (ignores nil values).
PRODUCT(1,2,3)
=>6 (1*2*3)
PRODUCT(1,nil)
=> 1
DIVIDE(values)
Divides the first value with the second value.
DIVIDE(1,2)
=> 0.5
DIVIDE(1,2,3,4)
=> 0.5 --> only takes the second.
MAX(values)
Returns the highest number.
MAX(-3,-2,5)
=> 5
MIN(values)
Returns the lowest number.
MIN(-3,-2,5)
=> - 3
ABS(values)
Returns all given numbers in absolute values.
ABS(-3,-2,5)
=> [3,2,5]
ROUND(value, precision = 0)
Public: Rounds numeric value to a given precision.
ROUND(3.334,2)
=> [3.33]
FLOOR(value, precision = 0)
Returns the largest number less than or equal to numeric value.
FLOOR(3.5)
=> 3
CEIL(value, precision = 0)
Returns the smallest number greater than or equal to numeric value.
CEIL(3.5)
=> 4
SQRT(values)
Returns the square root of the given values.
SQRT(4)
=> [2]
SQRT(4,9)
=> [2,3]
LESS(x,y)
Returns true when x is smaller than y. Note: This function only looks at the first two values entered in this function.
LESS(1,2)
=> true
LESS(2,1)
=> false
LESS(1,2,1)
=> true
LESS(1,2,5)
=> true
LESS_OR_EQUAL(x,y)
Returns true when x is smaller or equal than y. Note: This function only looks at the first two values entered in this function.
LESS_OR_EQUAL(1,2)
=> true
LESS_OR_EQUAL(1,1)
=> true
LESS_OR_EQUAL(2,1)
=> false
LESS_OR_EQUAL(1,2,1)
=> true
LESS_OR_EQUAL(1,2,5)
=> true
GREATER(x,y)
Returns true when x is greater than y. Note: This function only looks at the first two values entered in this function.
GREATER(1,2)
=> false
GREATER(2,1)
=> true
GREATER(2,1,1)
=> true
GREATER(2,1,5)
=> true
GREATER_OR_EQUAL(x,y)
Returns true when x is smaller or equal than y. Note: This function only looks at the first two values entered in this function.
GREATER_OR_EQUAL(1,2)
=> false
GREATER_OR_EQUAL(1,1)
=> true
GREATER_OR_EQUAL(2,1)
=> true
GREATER_OR_EQUAL(2,1,1)
=> true
GREATER_OR_EQUAL(2,1,5)
=> true
EQUALS(x,y)
Returns true when x is equal to y. Note: This function only looks at the first two values entered in this function.
EQUALS(1,1)
=> true
EQUALS(1,2)
=> false
EQUALS(1,1,5)
=> true
NOT
Returns true when x is not equal to y. Note: This function only looks at the first two values entered in this function.
NOT(1,1)
=> false
NOT(1,2)
=> true
NOT(1,1,5)
=> false
OR(values)
Takes any number of arguments and checks if any of the arguments are true. If any are true, the functions returns 'true'. If not, false is returned.
OR(true,false)
=> true --> true is one of the arguments.
OR(false,false)
=> false --> true is not one of the arguments
OR(3,3)
=> false --> true is not one of the arguments
IS_NUMBER(x)
Returns true when x is a number. Note: The value is only recognized when placed in brackets. Furthermore it only looks at the first element inside the brackets. While not using brackets, the function will expect one element.
IS_NUMBER(1)
=> Error
IS_NUMBER([3])
=> true
IS_NUMBER('three')
=> false
IS_NUMBER([3,'three'])
=> true
IS_NUMBER([3],'three')
=> Error: Wrong number of elements
IS_NIL (value)
Returns true when the given value is nil. False when the value is not nil.
NEG(x)
Returns the negative value of the given value. Note: Only the first value is taken into account.
NEG(1)
=> -1
NEG(1,2)
=> -1
NEG(-1,-2)
=> 1
UNIT(x,unit)
Converts a value to another format.
UNIT(0.15,percentage)
=> 15.0 (%)
INVERSE(x)
Returns the inverse of a given value. Note: Only the first value is taken into account.
INVERSE(5)
=> 0.2
INVERSE(5,2)
=> 0.2
FLATTEN(array)
Flattens any nested arrays into a single array with depth=1, removing nils
FLATTEN([[1],[2],[3]])
=>
[1,2,3]
EQUALS(values)
Checks if the first two values that are given are equal.
EQUALS(2,2)
=> true
EQUALS(2,3)
=> false
EQUALS(2,2,3)
=> true
EQUALS(2,3,3)
=> false
IF(condition, true_stmt, false_stmt)
If the condition is true, the true_stmt is returned, if the condition is false, the false_stmt is returned.
IF(EQUALS(1,1),3,4)
=> 3 --> EQUALS(1,1) returns 'true', so 3 is returned.
IF(EQUALS(1,2),3,4)
=> 4 --> EQUALS(1,2) returns 'false', so 4 is returned.
Core functions
The Core functions form the core of GQL. With these functions you can extract data from elements of the model.
V(args)
Shortcut for the LOOKUP and MAP function. Used to retrieve information from the energy graph.
Example with node.
V(foo) --> LOOKUP(foo)
=> foo
Example Lookup multiple nodes by their keys.
V(foo,bar) --> LOOKUP(foo,bar)
=> [<foo>, <bar>]
Example Lookup a node attribute.
V(foo,demand) --> MAP(LOOKUP(foo,demand))
=> 100 (When demand of node 'foo' is equal to 100)
Example nesting of LOOKUPs.
V(V(foo), V(bar), demand) --> MAP(LOOKUP(foo, LOOKUP(bar)), demand)
=> 100, 200
Example pass objects to V().
V(CARRIER(electricity), cost_per_mj) --> = MAP( LOOKUP(CARRIER(electricity)), cost_per_mj )
=> 23.3
MV(args)
Same functionalities as V, but used for the molecule graph.
Q(key)
QUERY() or Q() returns the result of a gquery with given key.
Q(total_costs)
=> 100
CHILDREN(nodes)
Outputs the nodes corresponding to the outgoing edges of the given node.
CHILDREN(V(households_space_heater_coal))
=> <Node households_final_demand_for_space_heating_coal>
PARENTS(nodes)
PARENTS(V(households_space_heater_coal))
=> <Node households_space_heater_coal_aggregator>
Outputs the nodes corresponding to the incoming edges of the given node.
QUERY_PRESENT(key)
Returns the present value of the the gquery, when given a key. If the argument is a lambda ( -> { ... }), it returns the present value of the query inside the lambda.
GRAPH(year)
=>
2019 2,019
2050 2,050
Q(graph_year)
=>
2019 2,019
2050 2,050
QUERY_PRESENT(graph_year)
=>
2,019
QUERY_PRESENT( -> { GRAPH(year) } )
=>
2,019
QUERY_PRESENT(GRAPH(year))
=>
error
QUERY_FUTURE(key)
Returns the present value of the the gquery, when given a key. If the argument is a lambda ( -> { ... }), it returns the present value of the query inside the lambda.
GRAPH(year)
=>
2019 2,019
2050 2,050
Q(graph_year)
=>
2019 2,019
2050 2,050
QUERY_FUTURE(graph_year)
=>
2,050
QUERY_FUTURE( -> { GRAPH(year) } )
=>
2,050
QUERY_FUTURE(GRAPH(year))
=>
error
QUERY_DELTA(key)
Returns the delta of the present value and future value of the query. Note: an operation within this query should be noted inside ( -> { ... }).
QUERY_DELTA(graph_year)
=>
2019: 0.0
2050 : 31
QUERY_DELTA( -> { GRAPH(year) } )
=>
2019: 0.0
2050 : 31
QUERY_DELTA(GRAPH(year))
=>
error
AREA()
Returns an attribute.
AREA(present_number_of_residences)
=> 7349500.0
LAST(values)
Returns the last element of the array.
LAST(V(1,2,3))
=>
3
FIRST(values)
Returns the first element of the array.
LAST(V(1,2,3))
=>
1
EDGE(lft,rgt)
Returns the edge that goes from the first (lft) to the second node (rgt) for the energy graph.
EDGE(energy_import_electricity,energy_interconnector_1_imported_electricity
)
=>
#<Qernel::Edge "energy_import_electricity-energy_interconnector_1_imported_electricity@imported_electricity">
MEDGE(lft,rgt)
Returns the edge that goes from the first (lft) to the second node (rgt) for the molecule graph. See EDGE() for functionality
EDGES()
Retrieves edges based on given node(s) and optional arguments to filter or specify the type of edges.
EDGES(V(foo))
=>
[foo->gas_1, foo->gas_2, loss1->foo, heat1->foo]
EDGES(V(foo), "share?")
EDGES(V(foo), "flexible?")
EDGES(V(foo), "flexible? && share >= 1.0")
=>
[Edges based on specified constraints]
EDGES(OUTPUT_SLOTS(foo, heat))
=>
[heat->foo]
EDGES(V(foo, bar))
=>
[Edges of multiple nodes]
OUTPUT_SLOTS()
Gets the output (to the left) slots of node(s). Can specify a particular type of slot or retrieve all output slots.
OUTPUT_SLOTS(foo)
=>
[(loss)-foo, (heat)-foo]
OUTPUT_SLOTS(V(foo))
=>
[(loss)-foo, (heat)-foo]
OUTPUT_SLOTS(V(foo, bar))
=>
[(loss)-foo, (heat)-foo, ...]
OUTPUT_SLOTS(foo, loss)
=>
[(loss)-foo]
INPUT_SLOTS()
Gets the input (to the right) slots of node(s). Can specify a particular type of slot or retrieve all input slots.
INPUT_SLOTS(foo)
=>
[foo-(gas), foo-(oil)]
INPUT_SLOTS(foo, gas)
=>
[foo-(gas)]
INPUT_EDGES()
Retrieves input edges based on given node(s) and optional arguments to filter or specify the type of edges.
INPUT_EDGES(V(foo))
=>
[All input edges of node 'foo']
INPUT_EDGES(V(foo), "share?")
INPUT_EDGES(V(foo), "flexible?")
INPUT_EDGES(V(foo), "flexible? && share >= 1.0")
=>
[Input edges based on specified constraints]
INPUT_EDGES(INPUT_SLOTS(foo, oil))
=>
[foo->oil_1]
INPUT_EDGES(V(foo, bar))
=>
[Input edges of multiple nodes]
OUTPUT_EDGES()
Retrieves output edges based on given node(s) and optional arguments to filter or specify the type of edges.
OUTPUT_EDGES(V(foo))
=>
[All output edges of node 'foo']
OUTPUT_EDGES(V(foo), "share?")
OUTPUT_EDGES(V(foo), "flexible?")
OUTPUT_EDGES(V(foo), "flexible? && share >= 1.0")
=>
[Output edges based on specified constraints]
OUTPUT_EDGES(OUTPUT_SLOTS(foo, heat))
=>
[heat->foo]
OUTPUT_EDGES(V(foo, bar))
=>
[Output edges of multiple nodes]
Curves functions
With these functions you can perform operations with curves from the merit modules.
CLAMP_CURVE(curve, min, max)
Restricts the values in a curve to be between the minimum and maximum. Raises an error if min > max.
CLAMP_CURVE([1,2,3,4],0,2)
=> [1,2,2,2]
CLAMP_CURVE([1,-2,3,-4],0,2)
=> [1,0,2,0]
COALESCE_CURVE(curve, default = 0.0, length = 8760)
If the given curve is an array of non-zero length, it is returned. If the curve is nil or empty, a new curve with the length of the value that is given to length is created, each value in the curve is set to the value that is given to default.
COALESCE_CURVE(nil,3,5)
=> [3,3,3,3,3]
COALESCE_CURVE(nil)
=> [0,0,0,...,0]
Since no values are given for default & length, these are set to 0 & 8760 respectively
CUMULATIVE_CURVE(curve)
Creates a new curve where each index (n) is the sum of (0..n) in the source curve.
CUMULATIVE_CURVE([1, 2,3,4])
=> [1,3,6,10]
CUMULATIVE_CURVE([1,-2,3,-4])
=> [1,-1,2,-2]
INVERT_CURVE(curve)
Inverts a single curve by swapping positive numbers to be negative, and vice-versa.
INVERT_CURVE([1, 2,3,4])
=> [-1,-2,-3,-4]
INVERT_CURVE([1,-2,3,-4])
=> [-1,2,-3,4]
SUM_CURVES(curves)
Adds the values in multiple curves.
SUM_CURVES([1, 2], [3, 4])
=> [4, 6]
SUM_CURVES([[1, 2], [3, 4]])
=> [4, 6]
PRODUCT_CURVES(left,right)
Multiplies two curves elementwise. Note that unlike SUM_CURVES, PRODUCT_CURVES expects exactly two arguments, each one a curve. An error will be raised if either parameter is an array of curves, or if the curves don't have matching lengths.
PRODUCT_CURVES([1, 2, 3], [4, 5, 6])
=> [4, 10, 18]
DIVIDE_CURVES(left, right)
Divides two curves elementwise. Note that unlike SUM_CURVES, DIVIDE_CURVES expects exactly two arguments, each one a curve. An error will be raised if either parameter is an array of curves, or if the curves don't have matching lengths.
DIVIDE_CURVES([1, 2, 3], [4, 5, 6])
=> [0.25, 0.4, 0.5]
SMOOTH_CURVE(curve, window_size)
Creates a smoothed curve using a moving average. curve is the curve you want to use as input, the window_size is the number of points the curve will be averaged over.
SMOOTH_CURVE([3,2,4,3],1)
=> [3,2,4,3] --> Returns the input curve since each point is averaged on only one point.
SMOOTH_CURVE([3,2,4,3],2)
=> [3,2.5,3,3.5] --> Returns a different curve since the window_size is bigger.
DATASET_CURVE(key)
Loads a curve from the dataset by key. Returns an array of 8760 numeric values representing the curve.
Usage:
DATASET_CURVE('weather/air_temperature')
# => [12.5, 12.3, 12.1, ...]
DATASET_CURVE('total_demand')
# => [1250.0, 1300.0, ...]
The key can be:
- A curve set path, e.g.
'weather/air_temperature','solar/pv' - A simple profile name, e.g.
'total_demand','buildings_heating' - A user-attached curve (if configured)
Helper functions
These functions can support the user in gaining a quick insight in the data. See the examples below for use cases of these functions.
SORT_BY(objects, arguments)
With SORT_BY nodes can be sorted on one of their attributes. The nodes will be sorted ascending to the value of the attribute. Ranking of the nodes will start from 0. Note that the value of the attribute will not be printed, see TXT_TABLE for this functionality.
SORT_BY(G(useful_demand),demand)
=>
[
#<Node industry_useful_demand_for_chemical_other_hydrogen_non_energetic> 0,
#<Node bunkers_useful_demand_ships> 1,
...,
]
TXT_TABLE(objects, *arguments)
With TXT_TABLE 1 or more attributes from a node group can be queried. The nodes in the given node group will be sorted alphabetically.
Within the GQL-sandbox users can choose how the view the table in 4 different modes:
- Table: Shows the table in standard GQL-sandbox format.
- Text: Shows the table in text-format.
- CSV: Shows the table in CSV (comma separated values) format.
- TSV: Shows the table in TSV (tab separated values) format.
Note: With 'key' the name of the node is printed.
Example (output in text format, for readability only the first 2 and last 2 rows of the table are shown):
TXT_TABLE(G(useful_demand),key,demand)
=>
+------------------------------------------------------------------------------+--------------------+
| key | demand |
+------------------------------------------------------------------------------+--------------------+
| agriculture_useful_demand_electricity | 40964534066.695656 |
| agriculture_useful_demand_useable_heat | 98697676910.08954
|... | ... |
| transport_useful_demand_trucks | 144749566437.32986 |
| transport_useful_demand_vans | 1280922944.4741797 |
+------------------------------------------------------------------------------+--------------------+
This function can be combined with SORT_BY, so that a quick overview of the nodes with the highest attributes can be found.
Example with SORT_BY (output in text format, for readability only the first 2 and last 2 rows of the table are shown):
TXT_TABLE(SORT_BY(G(useful_demand),demand),key,demand)
=>
+------------------------------------------------------------------------------+--------------------+
| key | demand |
+------------------------------------------------------------------------------+--------------------+
| industry_useful_demand_for_chemical_other_hydrogen_non_energetic | 0.0 |
| bunkers_useful_demand_ships | 0.0 |
|... | ... |
| industry_useful_demand_for_chemical_other_non_energetic | 414554538059.73004 |
| industry_useful_demand_for_chemical_refineries_crude_oil_non_energetic | 2650973321780.0 |
+------------------------------------------------------------------------------+--------------------+
EACH()
Lets the user run multiple queries.
EACH(
SUM(foo, ...),
SUM(bar, ...)
)
=>
[Results of SUM queries]
Set functions
These functions concern operations associated with graph theory.
ALL()
Returns an Array of all nodes in the energy graph.
MALL()
Returns an Array of all nodes in the molecule graph.
G(group)
Abbreviation of GROUP. Returns an Array of all nodes for a given energy graph group.
GROUP(apartments)
=>
[
#<Node households_useful_demand_for_space_heating_apartments_1945_1964>,
#<Node households_useful_demand_for_space_heating_apartments_1965_1984>,
#<Node households_useful_demand_for_space_heating_apartments_1985_2004>,
#<Node households_useful_demand_for_space_heating_apartments_2005_present>,
#<Node households_useful_demand_for_space_heating_apartments_before_1945>,
#<Node households_useful_demand_for_space_heating_apartments_future>,
]
MG(group)
Abbreviation of MGROUP. Returns an Array of all nodes for a given molecule graph group.
MGROUP(ccu_emitted)
[
#<Node molecules_production_synthetic_methanol_emitted_co2>,
]
EG(group)
Abbreviation of EDGE_GROUP. Returns an Array of all nodes for a given energy graph edge group.
EG(final_demand)
=>
[
#<Qernel::Edge "agriculture_final_demand_crude_oil-agriculture_burner_crude_oil@crude_oil">,
#<Qernel::Edge "agriculture_final_demand_hydrogen-agriculture_burner_hydrogen@hydrogen">,
...,
#<Qernel::Edge "transport_final_demand_for_road_lpg-transport_van_using_lpg@lpg">
]
MEG(group)
Abbreviation of MEDGE_GROUP. Returns an Array of all nodes for a given energy graph molecule edge group.
SECTOR(sector)
Returns an Array of nodes for a given energy sector.
SECTOR(households)
=>
[
#<Node households_apartments_useful_demand_for_space_heating>,
#<Node households_apartments_useful_demand_for_space_heating_after_insulation>,
...
]
MSECTOR(sector)
Returns an Array of nodes for a given molecule sector.
SECTOR(energy)
=>
[
#<Node energy_chp_supercritical_ccs_ht_waste_mix_captured_co2>,
#<Node energy_chp_supercritical_ccs_ht_waste_mix_co2>,
...
]
CARRIER(key)
Returns an Array of carriers for given key(s). Returns carriers belonging to the energy graph.
CARRIER(electricity)
=>
[
<Qernel::Carrier id:electricity key:electricity>,
]
MCARRIER()
Returns an Array of carriers for given key(s). Returns carriers belonging to the molecule graph. See CARRIER.
INTERSECTION(keys)
Returns the elements that are present in both the first and second arrays.
INTERSECTION( V(1,2,3) , V(2,3,4) )
=> [2, 3]
EXCLUDE(keys)
Returns an Array of elements of the first array excluding the second array.
EXCLUDE( V(1,2,3) , V(2,3,4) )
=> [1]
FILTER(collection, filter)
Imposes a filter. Can be used to impose a filter on node groups based on node attributes, see example.
FILTER(G(electricity_production),"geothermal_input_conversion > 0.0")
=>
[
<#Node energy_power_geothermal>,
]
Fever functions
These functions concern operations associated with the Fever module.
FEVER_DEMAND(groups)
Outputs the yearly summed demand curve of all consumers in the specified Fever group. The Fever groups that can be chosen from are: buildings_space_heating, households_hot_water and space_heating
FEVER_DEMAND(buildings_space_heating)
=>
[
3,863.9766278835864,
3,439.1984233894727,
...,
6,931.270889166959
]
FEVER_PRODUCTION(groups)
Outputs the yearly summed supply curve of all consumers in the specified Fever group. The fever groups that can be chosen from are: buildings_space_heating, households_hot_water and space_heating.
FEVER_PRODUCTION(buildings_space_heating)
=>
[
3,863.9766278835864,
3,439.1984233894727,
...,
6,931.270889166959
]
FEVER_PRODUCTION_CURVE_FOR_COUPLE(producer,consumer)
A yearly curve specifying the production of a producer node in Fever for a consumption node.
FEVER_PRODUCTION_CURVE_FOR_COUPLE(
V(households_space_heater_combined_network_gas),
V(households_useful_demand_for_space_heating_terraced_houses_1965_1984)
)
=>
[
941.3148533148487,
...,
1,068.1549289644927,
]
FEVER_DEMAND_CURVE_FOR_COUPLE(producer,consumer)
A yearly curve specifying the demand of a consumption node in Fever for supply of a production node. The difference between the FEVER_PRODUCTION_CURVE_FOR_COUPLE and the FEVER_DEMAND_CURVE_FOR_COUPLE is marked as a deficit.
FEVER_DEMAND_CURVE_FOR_COUPLE(
V(households_space_heater_combined_network_gas),
V(households_useful_demand_for_space_heating_terraced_houses_1965_1984)
)
=>
[
941.3148533148487,
...,
1,068.1549289644927,
]
FEVER_PRODUCTION_CURVE(node)
A yearly curve describing the production for a specific consumer or of a producer within Fever.
FEVER_PRODUCTION_CURVE(V(households_useful_demand_for_space_heating_semi_detached_houses_1985_2004))
=>
[
380.84562570105106,
...,
462.08107903258804
]
FEVER_DEMAND_CURVE(node)
A yearly curve describing the demand of a specific consumer or from producer within Fever. The difference between the FEVER_PRODUCTION_CURVE of a producer and the FEVER_DEMAND_CURVE from producer is marked as a deficit. The difference between the FEVER_PRODUCTION_CURVE for a consumer and the FEVER_DEMAND_CURVE of a consumer is marked as a deficit.
FEVER_DEMAND_CURVE(V(households_useful_demand_for_space_heating_semi_detached_houses_1985_2004))
=>
[
380.84562570105106,
...,
462.08107903258804
]
Update functions
These functions concern operations used to update values in the model.
UPDATE()
Updates attributes or elements based on the specified conditions or inputs, with various strategies (absolute, relative_total, or relative_per_year). Can be cobmined with the EACH function.
UPDATE(V(foo), demand, 100)
=>
Demand becomes 100
UPDATE(V(foo, bar, baz), demand, 5)
=>
Demand of all nodes becomes 5
EACH(
UPDATE(foo, ...),
UPDATE(bar, ...)
)
=>
[Results of UPDATE queries]
UPDATE_WITH_FACTOR()
Same as UPDATE, but the input value is expected to be a factor that the user supplies.
UPDATE_WITH_FACTOR(V(foo), preset_demand, 1.1)
=>
Foo gets a demand of 110.0
USER_INPUT()
Retrieves the numeric value of the user input, handling different formats (absolute, percentage, etc.).
USER_INPUT()
=>
3.0 (if the user input is "3")
INPUT_VALUE(key)
Retrieves the value of a specified input.
INPUT_VALUE('agriculture_geothermal_share')
=>
0.104
Constants
The constants are key figures that can be retrieved with GQL.
MWH_TO_GJ = 3.6
MONTHS_PER_YEAR = 12.0
HOURS_PER_YEAR = 8760.0
SECS_PER_HOUR = 3600.0
SECS_PER_YEAR = SECS_PER_HOUR * HOURS_PER_YEAR
KG_PER_TONNE = 1000
LITER_PER_BARREL = 159
MJ_TO_MHW = 3600
MJ_PER_KWH = 3.6
MJ_PER_MWH = 3600
BILLIONS = 10.0**9
MJ_TO_PJ = BILLIONS
MILLIONS = 10.0**6
THOUSANDS = 1000.0